One well known conventional abrasion tester has an abrasion wheel the circumference of which is covered with an abrasive. The wheel is pressed onto the surface of a sample to be tested, which is supported on a sample support, at a specific pressure and is reciprocated back and forth over the surface of the sample. The abrasion wheel is turned 0.9.degree. at every reciprocation by means of a ratchet and a pair of gear mechanisms connected to the abrasion wheel.
In this tester, the powder from the abrasive which is generated by the abrasion during the test falls onto and aheres to or remains on the surface of the sample being tested. This results in poor accuracy and reproducability of test results. Furthermore, because the means for driving the abrasion wheel is a complicated mechanism that executes reciprocating and fractional turning movements, it is difficult to make the surface of the sample and the surface of the abrasion wheel contact exactly parallel with each other. Therefore, the surface of the sample is liable to be only partly abraded, and the accuracy and reproducability of the test results is reduced even further.
Moreover, because a ratchet is used to turn the abrasion wheel through the predetermined angle at each reciprocation, and a pair of gears is used to transmit the turning movement, backlash which is inevitable in a gear mechanism, and which is caused by the reciprocating friction load due to the reciprocal movement of the abrasion wheel, badly affects the test results. Because the abrasion wheel tends to rotate back toward the former position at the end of every reciprocal movement due to the backlash, it is impossible to abrade the sample being tested perfectly evenly with a new abrasive surface on the next stroke of the abrasion wheel. These are all very serious drawbacks in the test apparatus.